Turbocharger control means

Abstract: Valve means to control the flow of charge air through a turbocharger intercooler by-pass (2), the valve means (1) having a valve (6) in the by-pass, actuating means (11) for the valve, and means (12) for sensing the charge air temperature, the sensing means being operatively coupled to the valve actuating means, (11), characterised by a valve (6) having a body (17) by which the valve can be mounted in the by-pass (2), a valve member (9, 15) movably mounted on the body (17) to close the by-pass, resilient means (10) on the body and urging the valve member into a position wherein the by-pass is open, and thermostatic means (11, 12) on the valve body for the sensing charge air temperature and for actuating the valve member (9, 15) to close the valve (6) when the sensed temperature reaches a given value.

Description: The invention relates to turbocharger control means and more particularly, but not exclusively, to means for the control of turbochargers for internal combustion engines such as reciprocating piston diesel engines. It is known to control the temperature of charge air entering a reciprocating piston diesel engine from an exhaust gas turbocharger, by passing the charge air first through an intercooler or radiator and to provide a by-pass which avoids the intercooler or radiator to prevent overcooling of the charge air in certain operating conditions, e.g. on start-up and at low ambient temperatures. It is known (e.g. from GB-A-1 255 956) for the by-pass to be controlled by means of a valve, e.g. a flap valve, under the operation of an actuator which is in turn controlled by a temperature sensor disposed in the engine inlet. This arrangement is costly and not easily adaptable to the needs of smaller engines, e.g. in commercial trucks. It is an object of the invention to provide valve means for controlling the intercooler radiator by-pass from an exhaust gas turbocharger to an engine inlet, which is simple and therefore inexpensive compared to the known control means. According to the invention, there is provided valve means for controlling an intercooler radiator by-pass comprising a valve for controlling flow of charge air through the by-pass and thermostatic means capable of sensing the charge air temperature at or near the engine inlet and causing the valve to open when the charge air temperature is low, the valve means being as described in claim 1. The valve means may be generally of the kind used for controlling the liquid coolant temperature of an internal combustion engine, ie a thermostatic valve. In the present case however it is preferred that the thermostatic valve works in the reverse sense to that normally found in an engine cooling system so that, should the valve fail, it fails safe, that is to say with the valve open. In an embodiment the temperature sensing means and valve actuating means comprises a wax-filled bulb. The valve member may be tubular or disc-like and may be arranged for axial movement on the valve body. The valve means preferably comprises a valve housing forming one end of the by-pass and in which the valve is mounted, the housing being formed with means, eg a shoulder or end face, against which the valve member can abut to close the by-pass. Preferably the housing forms the down-stream end of the by-pass whereby the temperature sensing means of the valve is positioned adjacent the engine inlet. From another aspect the invention is the combination of an internal combustion engine, an exhaust gas turbocharger, an intercooler through which charge gas from the turbocharger is passed to the engine, a by-pass for the intercooler, and valve means for controlling the by-pass, as described in claim 7. The invention is diagrammatically illustrated by way of example in the accompanying drawings in which:- Figure 1 illustrates a conventional (prior art) system for controlling a radiator intercooler by-pass from an exhaust gas turbocharger to an engine inlet; Figure 2 is a diagram generally similar to that of Figure 1 and showing a control arrangement in accordance with the present invention; Figure 3 is a sectioned scrap view of part of valve means for the control arrangement of Figure 2, and Figure 4 is a sectioned scrap view generally similar to that of Figure 3 and showing valve means particularly adapted for retro-fitting to existing engines. In the drawings there is shown means for controlling the temperature of the charge air entering an internal combustion engine, e.g. a reciprocating piston diesel engine, from an exhaust gas turbocharger. Figure 1 illustrates a known device in which a hot gas by-pass is provided which short-circuits a radiator or intercooler provided in the flow path from the turbocharger to the engine air inlet to cool the charge air. The by-pass enables high temperature charge air to pass directly to the engine inlet to avoid over cooling of the charge air as, for example, might occur on engine start-up in cold conditions. The hot charge air by-pass is under the control of a valve e.g. a flap valve, disposed in the by-pass and which is operated by an external actuator which is in turn controlled by an external temperature controller which is acted on by a temperature sensor provided in the engine air inlet. Such a mechanism can accurately control the charge air temperature but is expensive to produce. In addition the mechanism is largely external, which can cause difficulty in some automotive applications where space is limited. In Figure 2 there is shown means 1 for controlling the temperature of the charge air entering an internal combustion engine (not shown), e.g. a reciprocating piston diesel engine, from an exhaust gas turbocharger (not shown) in an arrangement in which a by-pass 2 is provided which short circuits a radiator or intercooler 3 provided in the flow path indicated by arrows 4 from the turbocharger to the engine air inlet 5 to cool the charge air. The by-pass 2, which is under the control of valve 6, enables high temperature charge air to pass directly to the engine inlet 5 to avoid over cooling of the charge air as, for example, might occur on engine start-up in cold conditions. The arrangement shown in Figure 2 is thus generally similar to that shown in Figure 1 but the valve mechanism including the actuator and temperature controller for controlling the hot charge air by-pass 2 is replaced by a thermostatic valve 6 disposed wholly within the by-pass 2 and/or inlet 5 and arranged to sense the charge air temperature adjacent to the engine inlet. As shown in Figure 3 of the drawings, the thermostatic valve 6 for the embodiment of Figure 2 is generally similar to those thermostatic valves known and used for many years to control engine coolant systems at start-up to reduce the time taken to achieve operating temperature. The thermostatic valve comprises a disc like mounting member 7 by which the valve body 17 is held in position in its housing 8 which forms one end of the by-pass 2 and which carries a movable valve member 9 which is constantly biased into an open position as shown in Figure 3 by resilient means eg a coil spring, 10 and which is drawn into a closed position (not shown) by drive means 11 which may, for example, comprise a bulb of wax, in known manner. The wax bulb forms the temperature sensing portion 12 of the thermostatic valve and is arranged for disposition in or near the engine air inlet 5 to sense the temperature of the inlet air. The thermostatic valve of the present invention is distinguished from the known arrangement used in engine coolant systems in that, in the present case, it is arranged to fail-safe, that is, with the valve member opening the hot air by-pass as shown in Figure 3 to prevent over cooling of the engine. The valve member 9 is an open ended hollow cylindrical or tubular body which is axially slidably mounted in the housing 8 with a seal 20 in the housing making sealing contact with the peripheral face of the valve member 9 whereby charge air passing through the valve 6 is constrained to pass through the tubular valve member 9. In operation, the valve member 9 closes to shut-off the by-pass 2 to prevent air from by-passing the intercooler when the temperature sensor 12 senses a sufficiently high temperature in the inlet 5. The valve member 9 closes by movement to the left as viewed in Figure 3 so that the cylindrical or tubular end 13 of the valve number 9 abuts against a plate like end 14 of the housing 8 to prevent air flow through the valve member 9 and thus through the by-pass 2. The arrangement shown in Figure 4 is generally similar to that described above with reference to Figures 2 and 3 but is intended for retro-fitting to existing engine/turbocharger/intercooler-radiator systems. The form of valve shown in Figure 4, in which the valve member 15 is disc-like, may be preferable in some instances to the arrangement shown in Figure 3 in which the valve member 9 is tubular, since it may enable the use of a relatively simple valve housing 16 compared to the relatively complex valve-housing as shown in Figure 3. In Figure 4 the valve member 15 is shown in dotted lines in its open position and is shown in full lines in the closed position, in which the disc 15 abuts against a shoulder 18 of the housing to close the by-pass 2. The invention thus provides a simple but effective mechanism for controlling a hot air by-pass of the kind described which is arranged to be disposed entirely internally of the by-pass and which is much less complicated than the known arrangement of Figure 1.

Claims: Valve means (1) to control the flow of charge air through a turbocharger intercooler by-pass (2), the valve means (1) having a valve (6) in the by-pass, actuating means (11) for the valve, and means (12) for sensing the charge air temperature, the sensing means being operatively coupled to the valve actuating means (11), characterised by a valve housing (8,16) defining a valve passage having an inlet and an outlet and adapted to form at least part of the said by-pass (2), a valve body (17) supported on the housing, a valve member (9,15) movably mounted in the body exclusively to control flow through the bypass, resilient means (10) on the body and urging the valve member (9,15) into a position wherein the bypass is open, actuating means (11) on the body for moving the valve member between open and closed positions and thermostatic means (12) on the body and extending beyond said valve passage for sensing charge air temperature, said thermostatic means being operatively coupled to the valve actuating means to cause the valve member to close the bypass when the sensed temperature reaches a given value. Valve means according to claim 1, characterised in that the temperature sensing means (12) and valve actuating means (11) comprises a wax-filled bulb. Valve means according to claim 1 or claim 2, characterised in that the valve member (9) is tubular and is arranged for axial movement on the valve body (17). Valve means according to any preceding claim, characterised by abutment means (14,18) in the valve housing (8) and against which the valve member (9, 15) can abut to close the by-pass. Valve means according to claim 3 and claim 4, characterised in that the tubular valve member is slidable in the valve housing (8), and in that the peripheral surface of the valve member is sealed against the housing by seal (20). Valve means according to claim 4 or claim 5, characterised in that the housing (8) forms the down-stream end of the by-pass (2) whereby the temperature sensing means (12) of the valve (6) can be positioned adjacent the engine inlet (5). The combination of an internal combustion engine, an exhaust gas turbocharger, an intercooler (3), a charge air passage through which charge gas from the turbocharger is passed to an inlet (5) for the engine via the intercooler, a by-pass (2) for the intercooler, and valve means (1) for controlling the by-pass, characterised in that the valve means (1) comprises a valve housing (5,16) defining a valve passage having an inlet and an outlet and adapted to form at least part of the said by-pass (2), a valve body supported on the housing, a valve member (9,15) movable mounted on the body exclusively to control flow through the valve passage, resilient means (10) on the body and urging the valve member into a position wherein the valve passage is open, actuating means (11) on the body for moving the valve member between open and closed positions and thermostatic means (12) mounted on the body and extending into the charge air passage for sensing charge air temperature in the engine inlet, said thermostatic means being operatively coupled to the valve actuating means to cause the valve member to close the bypass when the sensed temperature reaches a given value.

Inventors: FRANCIS JOHN PETER, FRANCIS, JOHN PETER
Applicants: AMOT CONTROLS LTD, AMOT CONTROLS LIMITED
Application year: 1994
Main classification: F02B29
IPC codes: F01P7, F02B29, F02B3